Lacquers based on acrylic polymer blends

ABSTRACT

THE LACQUER WHICH COMPRISES A BLEND OF TWO ACRYLIC POLYMERS IN A LIQUID CARRIER, THE DIFFERENCE BETWEEN THE GLASS TRANSITION TEMPERATURES OF THE POLYMERS BEING AT LEAST 30* C.

United States Patent Oflice 3,823,205 Patented July 9, 1974 ABSTRACT OF THE DISCLOSURE The lacquer which comprises a blend of two acrylic polymers in aliquid carrier, the difference between the glass transition temperatures of the polymers being at least30 C.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 588,699, filed July 23, 1969, which in turnis a continuation-in-part of application Ser. No. 509,147, filed Nov. 22, 1965,both now abandoned, and a continuation of Ser. No. 860,800, filed Sept. 24, 1969, now abandoned.

SUMMARY OF THE INVENTION This invention relates to coating compositions. It is more particularly directed to lacquers whose principal filmforming ingredients are two-component blends of acrylic polymers. The differences in glass transition temperature between the blends components is at least 30 C.

One component of these blends (Component A),

making up .at least 5% of the blends total weights, can

be po1y(methyl methacrylate), poly(ethyl methacrylate), poly(propyl methacrylate), poly(isopropyl methacrylate) or a copolymer of methyl methacrylate with at least one of an alkyl acrylate whose alkyl group contains 1 through 20 carbon atoms, an alkyl methacrylate whose alkyl group contains 2 through l8'carbon atoms, or styrene. Mixtures of these can be also used.

The other component of the blends (Component B),

also making up at least 5% of the blends total weights, is a two-monomeric component copolymer of methyl methacrylate with at least one of an alkyl acrylate whose alkyl group contains 1 through 10 carbon atoms or an alkyl methacrylate whose alkyl group contains 4 through 18 carbon atoms. Mixtures of these can also be used.

The diiference between the glass transition temperatnres (T of componnets (A) and (B) must be at least 30 C. Glass transition temperature is measured on a Diiferential Thermal Mechanical Analyzer, Model 900, sold by E. I. du Pont de Nemours and Company.

The compositions of the invention give finishes having 1 Water-snot-free temperature" is the highest temperature to which a finish can be heated, after placing a drop of tap water on the finish and evaporating it, without leaving a permanent spot.

Craze-free temperature is the lowest temperature at 1 which a drop of methylethyl ketone can be evaporated from the finish without producing craze marks.

formed from compositions whose film-forming components are conventional polymer systems. Surprisingly,

the compositions give these benefits while containnig 33% to 50% less plasticizer than usual.

5 These advantages make the compositions of the invention useful as automotive lacquers, where the high craze resistance and the high print resistance, (i.e., freedom from deformation under load at 150 F.) of their finishes are especially desirable.

Preferred for the excellence of the finishes they give are compositions in which components (A) and (B), as entities, have T, values of at least 0 C.

Also preferred for the excellence of the finishes they give are compositions in which component (B) has a glass transition temperature of at least 50 C.

Especially preferred for their excellence are compositions in which component (A) is poly(methyl methacrylate) and component (B) is at least one of (l) a methyl methacrylate/methyl acrylate copolymer whose monomer unit weight ratio is 70/30 to /60 respectively,

(2) a methyl methacrylate/ethyl acrylate copolymer whose monomer unit weight ratio is 80/20 to 40/60 respectively,

(3) a methyl methacrylate/butyl acrylate copolymer whose monomer unit weight ratio is 85/15 to /35 respectively,

(4) a methyl methacrylate/Z-ethylhexyl acrylate copolymer whose monomer unit weight ratio is 90/10 to 30 respectively,

(5) a methyl methacrylate/octyl methacrylate copolymer whose monomer unit weight ratio is 15 to 65/ 35 respectively, or

(6) a methyl methacrylate/lauryl methacrylate copolymer whose monomer unit weight ratio is /10 to 75/25 respectively.

Also preferred for their unique properties are compositions in which component (A) is a copolymer of methyl methacrylate and 5 butyl methacrylate octyl methacrylate lauryl methacrylate methyl acrylate ethyl acrylate butyl acrylate Z-ethylhexyl acrylate Excess is at least 0 When Comonomer is: (wt. percent units) 6 Butyl methacrylate 36 Octylmethacrylate 20 Lauryl methacrylate 10 Methyl acrylate 3 0.

.65 .Ethyl acrylate 20 Butyl acrylate 15 Z-Ethylhexyl acrylate 10 Most preferred as an automotive lacquer because of the 70 durability of the finish it gives is a composition comprising gh about 25 Factor CONVERSION CHART The coating compositions themselves are made by first selecting components (A) and (B) and their concentra- Illustrative of organic liquids which can be used are toluene, ketones such as acetone or methyl ethyl ketonc,

The compositions will ordinarily have solids contents of from about 20% to 40%, by weight of the total com- It is generally desirable to add a plasticizer to the compositions. Plasticizers compatible with poly(methyl meth- Styrene Factor tions in the compositions according to the properties wanted of the finish, and then thoroughly mixing solutions or dispersions of these components in organic able.

alcohols such as ethanol and isopropanol, or mixtures of these. Before use, the compositions are thinned to application viscosity with customary lacquer solvents.

position. Under certain conditions, compositions of the invention may separate into two phases on standing. Should this occur, it can be remedied by lowering solids content of the compositions or by using components of lower molecular weight.

acrylate), such as dibutyl phthalate,"bis-(methylcyclohexyl) phthalate, butyl benzyl phthalate, tributyl citrate, polyester plasticizers and alkyd resins are satisfactory.

concentration of from about 2% throu by weight, of the solids of the composition.

auryl meth- POSi- 5' Whichever plasticizer is used, it is ordinarily present at a owing Butyl L methrylate acrylate film-forming components, of po1y(methyl methacrylate)having a relative viscosity (0.5% solution in ethylene chloride) of 1.10-1.25;

film-forming components, of a methyl methacrylate/ butyl acrylate 82/18 or a 76.5/23.5 copolymer having a relative viscosity of 1.10/ 1.25,

tion, of a plasticizer.

In some cases, the preferred compositions may also Although only coating compositions based on blends Border-line compatibility describes polymers or cosignificantly from each other but which, when blended as 30 q g With Such other adjuncts as PP desir- Another way of defining this is to say that compositions The preparation of components (A) and (B) is simple The approximate glass transition temperature of any GLASS TEMPERATURE FACTORS 2-ethyl- Methyl Ethyl Butyl hexyl acrylate acrylate acrylate acrylate aerylate ac O 0 0 0 0 0 O LLLLLLL22 2 2 22 d from Rohm and Haas 0 0 0 0 O LLLLLL2 22 2 Z23 &3

O L0 0 QO O LLLLLLLL22 2 2 Z 0 0 0 0 QLLLLLL2222 23 3 3 &

(A) at least about 30%, by weight of the acrylic polymer (B) at least about 30%, by weight of the acrylic polymer and (C) up to 20%, by weight of the solids of the composicontain from 5% through 20%, by weight of the solids of composition, of cellulose acetate butyrate.

of particular acrylic polymers or coplymers have been described, it should be understood that the benefits of a finish having high print resistance, a low craze-free temperature and superior air-dry gloss, and the advantages of being able to prepare a commercially sprayable lacquer having high solids content can be had with any composition containing a two-component blend of acrylic polymers' or copolymers, so long as the polymers or copolymers of the components are of border-line compatibility.

polymers, which, as entities, have T values which differ entities and cast as a film from solution, give an optically clear film.

containing polymers of border-line compatibility are homogeneous in solution at ambient temperature, but on evaporation of the liquid phase at temperatures above 65 C. separate into two distinct phases on a submicroscopic scale (i.e., the phases can be seen only with an electron microscope). Needless to say, all blends of polymers, copolymers or mixtures coming within these de .tions are a part of the invention.

and straightforward. A skilled polymer chemist will be able to prepare them without difllculty, using well-known standard solution polymerization techniques and conventional catalysts.

particular polymer or copolymer to be used in a com tion of the invention can be calculated from the 011 tables 1 Percent not shown in this table can be obtaine pt; Philadelphia, Pa. 19105 g. Find the'percehtage of deslredmonomer and get the corresponding glass temperature ac or. 2. Add the temperature factors and get the actual glass temperature of a copolymer made irom these monomers from conversion chart below: .1.

a Factors for monomers Co.,'Special Products De Directions:

'Although the compositions canbe used as clear lacquers, they are ordinarily pigmented. Conventional pigments canbe used, in the usual amounts. The pigments are added to the compositions as mill bases, made in the usual way. With certain pigments, it may be desirable to prepare the' mill base in a solution of a terpolymer in an organic "liquid such as ketone, toluene, xylene, or mixtures of these. Two of the monomer units of this terpolymer can be any of those listed as monomer units for the copolymers of components (A) and (B). The third mono- The following examples are presented so that the invention can bemoreeasily practiced. These examples show only preferred embodiments of the invention. Variations :on these themes .can, of course, be composed by those skilled in the art by manipulating proportions and polymer compositions from what is shown. These variations are naturally considered to be part of the invention. In the examples, all parts areby weight and all relative' viscosities are determined from 0.5% solution in ethylene chloride.

, EXAMPLEI A lacquer is prepared by blending together y Parts Fob/(methyl methacrylate) solution (relative viscosity 1.17, T 105 C.) 40% solids in toluene/ acetone 70/30 Methyl methacrylate/butyl acrylate 82/ 18 copolymer solution (relative viscosity 1.17, T 61 C.)

40% solids in toluene/acetone 70/30 133.9 Alkyd resin solution, coconut oil/ ethylene glycol/ phthalic anhydride, 0.41/2.93/2.43, acid number 67-8, 70% solution in toluene Cellulose acetate butyrate (20 second viscosity) 1 15% solution in toluene/ acetone 70/30 Cellulose acetate butyrate (2 second viscosity) solution in toluene/acetone 70/ Pigment dispersion 2-Hydroxy-4-dodecyloxybenzophenone Silicone solution (Dow Corning DC-550) 2% solution in toluene Cellosolve acetate Acetone Parts t1 77.50 Mill Base 2 Prepared bysand-grinding p Peptized carbon black Polymethyl methacrylate a .111. Tolune /acetorie 70/30 6 Mill Base 3 Prepared by blending Aluminum flake 0.26

Polymethyl methacrylate 0.99

Toluene/acetone 70/30 2.01

Mill Base 4 Prepared by sand-grinding Green Gold pigment 0.22 Polymethyl methacrylate 0.35

Toluene/acetone 70/ 30 0.98

The lacquer is reduced with an equal volume of industrial lacquer thinner, sprayed on a conventionally primed auto body panel and then baked for 30 minutes at 300 F. to give a film about 2.3 mils thick.

The water-spot-free temperature of the resulting finish is 151 F. and the craze-free temperature is about 58 F., in contrast to corresponding temperatures of F. and 68 F. obtained with a finish of a similar lacquer containing only poly(methyl methacrylate) as the filmforming ingredient.

EXAMPLE 2 A lacquer is preparing by blending together Parts Poly(methyl methacrylate) solution (relative viscosity 1.17, T 105 C.) (40% solids in toluene/acetone 70/30) 76 Methyl methacrylate/butyl acrylate 76.5/23.5 copolymer solution (relative viscosity 1.13, T 58 C.) 40% solids as toluene/methylethyl ketone/isopropanol 70/17/13 Mill base* 202 Alkyd resin solution, coconut oil/ethylene glycol/ phthalic anhydride, 0.41/2.93/2.43, body A-B,

acid number 6-8, 70% solution in toluene 71 Cellulose acetate butyrate solution, 25% in toluene/ acetone 70/30 198 Cellosolve acetate 29 Acetone 29 *Prepared by Sand-grinding Monastral blue pigment 12.6 Indanthrone blue pigment 4.0 Carbon black 2.1 Aluminum flake 0.7

Poly(methyl methacrylate) solution as above 130.3

Toluene 36.2 Xylene 16.1

*Madeb sandrindin 'liO g g 40.0

2 Methyl methacrylate/ethyl acrylate/methacrylic acid terpolymer 60/38/2 4.0 Methylethyl ketone/acetone/toluene/xylene 2/2/ This lacquer is thinned to a viscosity of 30-35 seconds (No. 1 Zahn Cup) with an acetone/cellosolve acetate/ toluene 22.5/ 34/ 43.5 mixture. The composition is sprayed on a metal panel and baked for 30 minutes at 275 F. to give a finish 2.5 mils thick.

This finish has a water-spot-free temperature of 159 F. in contrast to 139 F. obtained with a finish of a similiar lacquer containing only poly(methyl methacrylate) as a film-forming ingredient. It also has a craze-free temperature of less than 56 F., as contrasted with a crazefree temperature of more than 70 F. obtained with a finish of the same poly (methyl methacrylate) lacquer.

EXAMPLE 4 An automotive lacquer is prepared by blending together Parts Methyl methacrylate/butyl acrylate 95/5 copolymer (relative viscosity 1.20, T 100 C.) 40% solution in acetone/toluene 40/60 142 Methyl methacrylate/butyl acrylate 76.5/23.5 copolymer (relative viscosity 1.13, T 58 C.) 40% solution in methylethyl ketone/toluene/isopropa- 1101 17/70/13 247 Coconut oil alkyd resin solution of Example 1 71 Mill base of Example 1 202 Acetone 66 Cellosolve acetate 66 This lacquer was diluted to a viscosity of 30-34 seconds (No. 1 Zahn Cup) with lacquer thinner, sprayed on a panel primed with a conventional automobile undercoat and then baked at 300 F. for 30 minutes to give a finish 2.5 mils thick.

This finish had a water-spot-free temperature of 149 F. and a craze-free temperature of 50 F. as contrasted with corresponding temperatures of 134 F. and 70 F. obtained with a finish of a similar lacquer containing only poly(methy1 methacrylate) as a film-forming ingredient.

EXAMPLE 5 A lacquer is prepared by blending together Parts Poly(methyl methacrylate) solution (relative viscosity 1.17, T 105 C.) 40% solids in toluene/acetone 70/30 Methyl methacrylate/Z-ethylhexyl acrylate 80/20 copolymer solution (relative viscosity 1.20, T 42 C.) 40% solids in toluene/acetone 70/30 40 To this blend are added 20 parts of a 40% solution of bis(benzyl)triethylene glycol phthalate in toluene. The composition is thoroughly mixed, thinned to spray viscos- 8 ity with lacquer thinner, sprayed on a metal panel and then baked for 30 minutes at 200 F..

The resulting finish has a print-free temperature .of 122 F. and a craze-freetemperature of 59 F., as contrasted with corresponding temperatures of 103 F. and 67 F. obtained with a finish of a similar lacquer containq ing only poly(methyl methacrylate) as a film-forming ingredient. v 1 q I claim:

1. A lacquer solution comprising p p I. As a film-forming component (A) at least one of 1) poly(methyl methacrylate),

(2) poly(ethyl methacrylate),

(3) poly(propyl methacrylate),

(4) poly(isopropyl methacrylate), v

(5 a copolymer composed only of methyl methacrylate and at least one of an alkyl acrylate whose alkyl group contains 1 through 20 carbon atoms, an alkyl methacrylate whose alkyl group contains 2 through 18 carbon atoms, or styrene, i

(6) mixtures of these, and

(B) at least one of I (1) a copolymer composed only of methyl methacrylate and an alkyl acrylate Whose alkyl group con-' tains 1 through 10 carbon atoms or an alkyl methacrylate whose alkyl group contains 4 through 18 carbon atoms, or i v (2) mixtures of said copolymers; and

II. an inert organic solvent for (A) and (B); each'of (A) and (B) being present in conceutrationsofat least 5% of their total weight; the dilference between the glass transition temperatures of (A) and (B) being at least 30 C., (A) and (B), when blended as entities and cast from solution, giving an optically clear film. I

2. A composition according to claim 1 wherein (A) and (B) have glass transition temperatures of at least 0 C.

3. A composition according to claim 1 wherein the glass transition temperature of (A) is at least 50 C.

4. A composition according to claim 3 wherein (A) isa copolymer of methyl methacrylate and a comonomer X (as listed below), and (B) is a copolymer of methyl methacrylate and the same comonomer X (as listed be loW), the weight percent of comonomer X in (B) exceeding the weight percent of comonomer X in (A) according to the following table: 1

Excess is at least When X is (wt. percent units). Butyl methacrylate 36 Octyl methacrylate -20 Lauryl methacrylate 10 Methyl acrylate 30 Ethyl acrylate 2 0 Butyl acrylate 15 2-ethylhexyl acrylate '10 whose monomer unit weight ratio is -15 to 65/35 respectively, (4) a methyl methacrylate/2-ethylhexyl acrylate copolymer whose monomer unit weight ratio is /10 to 70/ 30 respectively, f (5) a methyl methacrylate/Octyl methacrylate copolymer whose monomer unit weight "ratio is 85/ 15 to 65/35 respectively, or

(6) a methyl methacrylate/lauryl methacrylate copolymer whose monomer unit weight ratio is 90/10 to 75/25 respectively.

6. A coating composition according to claim 3 also containing a plasticizer.

7. A coating composition according to claim 5 wherein (B) is a methyl methacrylate/butyl acrylate copolymer whose monomer unit weight ratio is 85/15 to 65/35 respectively.

8. A coating composition according to claim 5 wherein (B) is a methyl methacrylate/butyl acrylate copolymer whose monomer unit weight ratio is 76.5/23.5 respectively, the components having relative viscosities of from 1.10 through 1.25.

9. A coating composition according to claim 5 wherein (B) is a methyl methacrylate/butyl acrylate copolymer whose monomer unit weight ratio is 82/ 18 respectively, the components having relative viscosities of from 1.10 through 1.25.

10. An article bearing a film derived from the composition of claim 1.

11. An article bearing a film derived from the composition of claim 2.

12. An article bearing a film derived from the composition of claim 3.

13. An article bearing a film derived from the composition of claim 4.

14. An article bearing a film derived from the composition of claim 5.

15. An article bearing a film derived from the composition of claim 6.

16. An article bearing a film derived from the composition of claim 7.

17. An article bearing a film derived from the composition of claim 8.

18. An article bearing a film derived from the composition of claim 9.

References Cited UNITED STATES PATENTS 3,249,463 5/1966 Carle 117-76 2,947,716 8/1960 Cornell et a1. 26041 2,940,950 6/1960 Gushman 26032.8

MURRAY THJLMAN, Primary Examiner C. I. SECCURO, Assistant Examiner US. Cl. X.R.

117--132, C, 161 UZ, 161 UC; 26016, 17 R, 31.8 M, 32.8 R, 33.4 R, 33.6 UA, 41 R, 41 C, 41 B 

